Process for the production of alkylor cycloalkyl tin halides

ABSTRACT

THIS INVENTION RELATES TO AN IMPROVED PROCESS FOR THE PRODUCTION OF ALKYL-OR CYCLOALKYL TIN HALIDES BY THE DIRECT REACTION OF METALLIC TIN WITH ALKYL-OR CYCLOALKYL HALIDES, COMPRISING CARRYING OUT THE REACTION IN THE PRESENCE OF AN ORGANO-ANTIMONY COMPOUND, OR A MIXTURE CONSISTING OF ORGANO-ANTIMONY COMPOUNDS AS A CATALYST.

United States Paten 3,595,892 PROCESS FOR THE PRODUCTION OF ALKYL- R CYCLQALKYL TIN HALIDES Jan W. G. van den Hurk, Utrecht, Netherlands, assignor to Nederlandse Centrale Organisatie voor Toegepast- Natuurwetenschappelijk Onderzoek, The Hague, Netherlands No Drawing. Filed July 15, 1968, Ser. No. 744,701 Claims priority, application Netherlands, July 18, 1967, 6709983 Int. Cl. C07f 7/22 US. Cl. 260-429.7 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved process for the production of alkylor cycloalkyl tin halides by the direct reaction of metallic tin with alkylor cycloalkyl halides, comprising carrying out the reaction in the presence of an organo-antimony compound, or a mixture consisting of organo-antimony compounds as a catalyst.

The present invention relates to a process for the production of alkylor cycloalkyl tin halides, respectively, by the direction reaction of metallic tin with alkyland cycloalkyl halides, respectively, or mixtures of alkyland/or cycloalkyl halides.

In the technical production of alkyl tin halides, the direct reaction of metallic tin with alkyl halides otters considerable advantages over the methods already known in which tin tetrachloride is used as the starting material, which is converted either with a Grignard compound or with an alkyl aluminum compound into the tetra-alkyl tin compound, from which the desired alkyl tin halide is produced in a second reaction step by means of a disproportionation reaction with tin tetra halide.

A number of processes for the direct reaction of metallic tin with alkyl halides in which use is made of highly reactive alkyl halides, especially iodides, is already known. However, in most cases these iodides are too expensive for the technical production of alkyl tin halides; therefore, there is a need for a process by which the cheaper alkyl bromides and especially alkyl chlorides can be directly converted with high yields to the corresponding alkyl tin halides. According to a process which is also known, this can be achieved by using arsenic or antimony halides as a catalyst for the reaction, but the process concerned mainly aims at the conversion of higher alkyl halide homologues, i.e. alkyl halides in which the alkyl group contains more than four carbon atoms. In another known process, for the production of alkyl tin halides, the reaction may be carried out in the presence of an alcohol, an ether, an ester or tetrahydrofuran and in the presence of certain metals and/or alkyl metal halides. The necessity of using specific solvents, however, is a serious drawback of this known process.

An improved process has now been found for the production of alkyl tin halides by direct reaction of metallic tin with alkyl halides, by means of which process both alkyl bromides and alkyl chlorides with lower alkyl groups, such as the ethyl-, propyland butyl compounds, and alkyl bromides and alkyl chlorides with higher alkyl groups, such as the hexyl-, heptyland octyl compounds, as well as cycloalkyl halides, such as the cyclohexyl compounds, can be converted to mixtures of the corresponding alkyland cycloalkyl tin halides, respectively, with good yields, and without the necessity of using specific solvents.

According to this invention the process for the production of alkyl or cycloalkyl tin halides by the direct reaction of metallic tin with alkylor cycloalkyl halides, respectively, or mixtures of alkyl and/or cycloalkyl halides at higher temperatures, is characterised by the fact, that the reaction is carried out in the presence of a catalytic amount of an organo-antimony compound or a mixture consisting of organo-antimony compounds.

In general, when this process is used, the dialkyland dicycloalkyl tin dihalides, respectively, are obtained as the main product of the reaction, whereas the monoalkyland monocycloalkyl tin trihalides, respectively, are formed as by-products, as well as, most often in smaller quantities, the trialkyland tricycloalkyl tin monohalides, respectively.

By the term organo-antimony compound is meant a compound of trivalent or pentavalent antimony, in which at least one alkyl-, alkenyl-, cycloalkyl-, aryl-, alkarylor aralkyl group is directly bonded to an antimony atom. If there are two or more of the said groups in the compound, these groups may diifer. Compounds of a more complex structure, such as tetraorgano diantimony compounds or complexes of tetraorgano antimony with metal halides or with halogens, are also included in the above definition.

The following are examples of organo-antimony compounds, which may be used as catalysts according to this invention: triethyl antimony, tri-n-butyl antimony, tri-isobutyl antimony, di-n-butyl antimony bromide, dim-butyl antimony chloride, monobutyl antimony dibromide, ethyl dibutyl antimony, tetrabutyl antimony bromide, tri-butyl antimony dibromide, diethyl tributyl antimony, tri-n-octyl antimony, di-noctyl antimony bromide, divinyl antimony bromide, tricyclohexyl antimony, triphenyl antimony, diphenyl antimony chloride, phenyl antimony dibromide, tetraphenyl antimony bromide, tolyl antimony dibromide, tribenzyl antimony, tetraphenyl diantimony, bis(tetrabuty1 antimony) .mercuric iodide-complex bis(tetraphenyl antimony).germanium iodide bromidecomplex [{(C H Sb} 'GeI Br tetraphenyl antimony iodide.iodine-complex [(C H SbI.I etc.

In the process according to this invention, the organoantimony compounds are mostly added in amounts varying from 1 to 8 mol. percent, calculated on the tin used, preferably in amounts from 3 to 5 mol. percent. In general, it is advisable to use, as a catalyst, an organo-antimony compound in which the organic group(s) is (are) the same as the alkylor cycloalkyl group, respectively, in the halide to be converted.

Furthermore, it was found that it may be of advantage, in order to improve the conversion of the less reactive alkyland cycloalkyl halides, respectively, i.e. the bromides and chlorides, to add to these a small amount of elementary iodine or of an inorganic or organic iodide, e.g. an amount of 0.5 to 10 mol. percent, preferably of 1 to 3 mol. percent, calculated on the bromide or chloride present. In this way, to give an example, it is advantageous to add an alkylor cycloalkyl iodide, respectively, in which the organic group is the same as that in the alkylor cycloalkyl bromide or alkylor cycloalkyl chloride used. The iodide can also be added in the form of an alkylor cycloalkyl tin iodide, respectively, e.g. as dialkyl tin diiodide or tin tetraiodide.

The process according to this invention may be carried out using the amounts of alkylor cycloalkyl halide, respectively, and tin in proportions which can be varied within wide limits. In this way, it is possible to use molecular ratios of e.g. alkylor cycloalkyl halides, respectively, to tin of 2:1 to 3:1, but also smaller or larger molecular ratios may be used.

The form and quality of the tin used as the starting material are not determinative for the carrying out of the process. In most cases, it is possible to achieve a very good reaction when using tin in the form of fine shavings but is is also possible to use fine or coarser powdered tin as the starting material.

In general, the reaction is carried out at temperatures between 130 and 210 C.; the reaction temperature is preferably chosen between 160 and 180 C. The process can be carried out both in a closed system under pressure and in an open system under atmospheric pressure, in which case the evaporating liquid is recycled by means of a reflux condenser. However, in the latter case, it is advisable, in particular for the conversion of the lower alkyl halides, to add inert solvents with a high boiling point so as to increase the reaction temperature.

In addition, in order to achieve as high a yield as possible, it is important, in those cases in which a catalyst sensitive to air is used, that the reaction be carried out in an inert atmosphere, e.g. under nitrogen.

The reaction mixture obtained can be further processed and the alkylor cycloalkyl tin halides, respectively, can be purified according to known processes, e.g. by means of distillation. For an analytical determination of the composition of the mixture good use can be made of the gas chromatographic method.

Any al-kylor cycloalkyl halide, respectively, used in excess can practically entirely be recovered by distillation and used for a subsequent reaction, just as any solvents added. It was also found, that the antimony-containing residue from the distillation can often be advantageously used as a catalyst for a subsequent reaction.

The alkylor cycloalkyl tin halides, respectively, obtained according to the process of the present invention, in particular the dialkylor dicycloalkyl tin dihalides, constitute valuable intermediates for the preparation of alkylor cycloalkyl tin compounds, respectively, which are applied as plastics additives. The monoalkylor monocyclo alkyl tin trihalides, respectively, and the trialkylor tricycloalkyl tin monohalides, respectively, which are formed as by-products of the process, also are valuable intermediates as such, but it is also possible to convert these compounds into the dialkylor dicycloalkyl tin dihalides, respectively by means of a disproportionation reaction, possibly by adding an amount of tetra-alkyl tin, or tetracycloalkyl tin, respectively.

The invention is further illustrated by means of the following examples.

EXAMPLE 1 6.0 g. pure tin in the form of fine shavings (0.1 to 0.3 mm. thick) and 21.0 g. n-butyl bromide are introduced into a Carius tube. After the air has been displaced by nitrogen 0.5 g. di-n-butyl antimony bromide is added and the tube is next heated under autogenous pressure at 180 C. for 16 hours, during which the tin completely goes into solution.

The contents of the tube are filtered off after cooling and the excess of butyl bromide is dis-tilled off under reduced pressure. Part of the residue is methylated quantitatively and the mixture of methylbutyl tin compounds thus obtained is analysed chromatographically.

The analysis results show that of the tin added 63.0% has been converted into di-n-butyl tin dibromide and 24.8% into n-butyl tin tribromide and that no determinable amount of tri-n-butyl tin bromide is formed.

4 EXAMPLE 2 In the same way as described in Example 1, a test is made in which 6.0 g. tin and 21.0 g. n-butyl bromide are heated without any further addition being made. Even after 16 hours, no tin has been converted. This clearly shows the catalytic action of the organo-antimony compound.

EXAMPLE 3 A mixture of:

Tin 6.0 n-Bu tyl bromide 21. n-Butyl iodide 2.0

and Tri-n-butyl antimony 0.5

is heated under autogenous pressure for 16 hours at180 C. in a Carius tube, in which the air has been displaced by nitrogen. After the experiment has been completed, the reaction mixture is further processed in the same way as described in Example 1.

The analysis results show that of the tin added 70.6% has been converted into di-n-butyl tin dibromide and 14.3% into n-butyl tin tribromide and that no determinable amount of tri-n-butyl tin bromide is formed. In comparison with Example 1, this result shows the favourable effect of the addition of the alkyl iodide on the conversion into the dialkyl tin dihalide'.

EXAMPLE 4 With a mixture of the following composition:

Tin 6.0

n-Butyl chloride 14.1

n-Butyl iodide 2.0

and

Tri-n-butyl antimony 0.5

separate tests are carried out in a Carius tube for 16 hours at temperature of and 200 0., respectively. The following table summarizes the yields of butyl tin chlorides, calculated from the analysis results of the reaction mixtures obtained, based upon added tin:

Degrees centigrade 140 160 180 200 n13utyl tin trichloride, percent". 11.5 12. 5 7. 5 D1:1'1-bl1l3yl tin dichloride, percent. 55. 8 72. 7 24. 4 Tn-n-butyl tin chloride, percent 9. 5

Total butyl tin chlorides, percent 20 76. 8 85. 2 31. 9

1 N 01; separately determined.

From these results it appears that the reaction has an optimum effect in the temperature range of 160 to 180 C.

EXAMPLE 5 A mixture of the same composition as indicated in Example 4, in which the tri-n-butyl antimony is replaced by triphenyl antimony, after being heated at 180 C. for 16 hours gives the following yields based upon added tin: di-n-bu-tyl tin dichloride 53.8%, n-butyl tin trichloride 19.6% and tri-n-butyl tin chloride nil.

is heated for 16 hours at 180 in a Carius tube in which the air has been displaced by nitrogen. On completion of the experiment, 90% of the tin added has been converted a yield of 65.4% of di-n-bu-tyl tin dichloride and a yield of 6.2% of n-butyl tin trichloride, based upon converted tin, being obtained.

EXAMPLE 7 A mixture of: G. Tin 6.0 n-Octyl bromide 24.9 n-Octyl iodide 2.0

and Tri-n-butyl antimony 0.5

is heated in a Carius tube for 16 hours at 180 C. in the same way as described above. A total yield of 80.2% of n-octyl tin bromides, based upon added tin, is obtained.

EXAMPLE 8 In the same way as described in the previous examples, a mixture of:

Tin 6.0

Cyclohexyl bromide 24.5

and

Tri-butyl antimony 0.5

is heated in a Carius tube for 16 hours at 180 C. On com.- pletion of the experiment, it appears that 45% of the tin added has been converted into a mixture of cyclohexyl tin bromides.

A test, carried out with an identical mixture, to which 1.38 g. I has been added, shows a conversion of 48.3% of the tin added.

EXAMPLE 9 A mixture of: G. Tin (shavings of 0.1-0.3 mm.) 6.0 n-Octyl bromide 58.0

and Bis (tetra-n-buytl antimony) -mercuric iodide-complex 2.0

In an autoclave, which is provided with a. stirring mechanism, a mixture of:

Tin (powder of 0.1-0.3 mm. grain size) 100.0

n-Butyl chloride 235.0

n-Butyliodide 33.0

and

Tri-n-butyl antimony 9.5

is introduced after the air in the autoclave has been replaced by nitrogen. The autoclave is next heated at 175 C. for three hours, whilst the stirrer is rotated at a velocity of 480 rotations/min. During the reaction the pressure rises to approx. 9 kg./cm.

After cooling, the contents of the autoclave is processed as described in the foregoing examples. The results of this experiment show that 85.7% of the tin added is converted, whereby a yield of 71.5% di-n-butyl tin dichloride, 12.8% n-butyl tin trichloride and 9.0% tri-n-butyl tin chloride is obtained.

1 claim:

1. 1n the process for the production of alkyl or cycloalkyl tin halides which comprises reacting metallic tin with an organic halide selected from the group consisting of alkyl halides and cycloalkyl halides at elevated temperatures in the presence of a catalyst for the reaction, the improvement which consists in conducting said reaction in the presence of from 1 mol percent to 8 mol percent, based on the amount of tin, of an organo-antimony compound selected from the group consisting of (a) trivalent and pentavalent antimony compounds having at least one organic group selected from the group consisting of alkyl, alkenyl, cycloalkyl, phenyl, tolyl, and benzyl bonded directly to the antimony and the remaining bonds of said trivalent and pentavalent antimony being bonded directly to a group selected from the group consisting of the aforesaid organic groups and halogen, (b) diantimony compounds having four organic groups selected from the group consisting of alkyl, alkenyl, cycloalkyl, phenyl, toluyl and benzyl bonded directly to the two antimonys, and (c) complexes of antimony compounds having four organic groups selected from the group consisting of alkyl, alkenyl, cycloalkyl, phenyl, toluyl and benzyl bonded directly to the antimony, with metal halides and halogens, as said catalyst for the reaction.

2. The process of claim 1 wherein said organo-antimony compound catalyst is present in an amount of from 3 mol percent to 5 mol percent.

3. The process of claim 1 wherein said organo-antimony compound catalyst contains only alkyl or cycloalkyl groups corresponding to said organic halides selected from the group consisting of alkyl halides and cycloalkyl halides.

4. The process of claim 1 wherein said elevated temperature is between C. and C.

5. The process of claim 1 wherein part of said organoantimony compound catalyst is the antimony-containing distillation residues from a previous reaction.

6. The process of claim 1 wherein said organic halides are selected from the group consisting of chlorides and bromides.

7. A process for the production of n-butyl tin chlorides which consists essentially of reacting metallic tin with n-butyl chloride in a molecular ratio of 1:2 to 1:3 in the presence of from 3 mol percent to 5 mol percent, based on the amount of tin, of tri-n-butyl antimony and in the presence of from 0.5 mol percent to 10 mol percent, calculated on the amount of n -butyl chloride, of n-butyl iodide, at a temperature of between. 160 C. and 180 C and recovering said n-butyl tin chlorides.

References Cited UNITED STATES PATENTS 3,085,102 4/1963 Yatagai et a] 260-429] 3,297,732 1/1967 Banks 260429.7 3,387,012 6/1968 Jasching et a1 260--429.7

TOBIAS E. LEVOW, Primary Examiner W. F. W. BELLAMY, Assistant Examiner 

